BAKE for 20 to 30 minutes or until golden brown. Let cool in pan for 10 minutes; remove to wire rack to cool completely.

MICROWAVE remaining morsels in small, microwave-safe bowl on MEDIUM-HIGH (70%) power for 1 minute; STIR. Morsels may retain some of their shape. If necessary, microwave at additional 10- to 15-second intervals, stirring until melted; spread over cookie. Decorate with icing.